The present invention relates to a liquid crystal display device having a direct light backlight structural body on a back surface of a liquid crystal panel, and more particularly to the joint structure of a back plate which constitutes the backlight structural body and a side mold frame which supports a fluorescent tube. To be more specific, the present invention relates to the foreign-material-intrusion preventing structure for preventing the intrusion of foreign materials from a joint portion of a raised portion of a reflection sheet which is mounted on a side wall portion of the back plate and an end portion of the side mold frame.
As a display device for a television receiver set or an information digital assistant, a liquid crystal display device has been popularly used. Generally, in this type of liquid crystal display device which is relatively large-sized and is required to possess a screen with high brightness, as a backlight structural body which constitutes an auxiliary illumination device of the liquid crystal display device, a so-called direct light backlight structural body which arranges a plurality of linear light sources on a back surface of the liquid crystal display panel and directly radiates light from the linear light sources on the back surface of the liquid crystal display panel is adopted. Here, “direct-light-type” is an expression which is used in contrast with a so-called side light backlight structural body which performs illumination by arranging a linear light source similar to the above-mentioned linear light source on a side of a light guide plate which is mounted on a back surface of the liquid crystal display panel.
The direct-light-type backlight structural body is mainly constituted of a reflection sheet which is arranged in a state that the reflection sheet faces a back surface of a liquid crystal display panel, a light diffusion plate which is arranged on a front surface side of the reflection sheet, and fluorescent lamps which are arranged between the reflection sheet and the light diffusion plate. These constitutional members are integrally formed with each other using a back surface plate which is formed in an approximately trough shape, a side mold frame which is mounted on the back surface plate, a frame-shaped mold frame in which the back surface plate which mounts the side mold frame thereon is fitted and the like, for example.
To be more specific, for example, the reflection sheet is mounted on the back surface plate formed in a substantially trough shape. Alternatively, a laminate plate which is formed by laminating a reflection sheet on a relatively hard metal sheet is formed in a substantially trough shape, and the reflection sheet is fixed to the back surface plate by adhering or mounting the approximately trough-shaped laminate plate to a bottom portion, a side wall portion and the like of the approximately trough-shaped back surface plate. The fluorescent lamps are supported on the side mold frame which is mounted on the back surface plate. Further, a diffusion plate has a peripheral portion thereof sandwiched by the back surface plate and the mold frames.
In general, with respect to the direct-light-type backlight structural body, in a relatively large-sized liquid crystal display device, a large-sized sheet has been used as the above-mentioned reflection sheet. However, it is difficult to neatly adhere the large-sized reflection sheet to the back surface plate using a double-sided adhesive film. Further, there exists a drawback that a cost of the laminate plate becomes high.
For overcoming such drawbacks, following patent document 1 (JP-A-2006-114445) discloses a direct-light-type backlight structural body which can facilitate mounting of a reflection sheet on a back surface plate at a low cost by enabling the reflection sheet to move relative to the side mold frame in the direction parallel to a surface of the back surface plate which faces the fluorescent lamps.